The epigenetic silencing of microRNA-433 facilitates the malignant phenotypes of non-small cell lung cancer by targeting CREB1

Objective: MicroRNAs (miRNAs) play a big role in the regulation of non-small cell lung cancer (NSCLC) development. The objective of this study is to determine how DNA methylation regulates miR 433 in NSCLC. Methods: The degree of DNA methylation was determined, and the relevance of miR-433 and the features of NSCLC patients were assessed. The MiR-433 and CREB1 expressions were tested, and the biological characteristics of the NSCLC cells were determined. Subcutaneous tumorigenesis in nude mice and luciferase activity assays were performed. Results: MiR-433 was downregulated, and CREB1 was upregulated in the NSCLC tissues, and the methylating rate of the C-phosphate-G (CpG) island in the miR-433 promoter region was enhanced. MiR-433 was also downregulated, and CREB1 was upregulated in the NSCLC cells and there was a low degree of promoter methylation of miR-433 in the NSCLC cells after demethylation. Upregulated miR-433 or downregulated CREB1 repressed the cell vitality and colony formation abilities and increased the amount of apoptotic A549 cells. Moreover, upregulated miR-433 also decelerated tumor growth. Conversely, the H460 cells and xenografts with reduced miR-433 or overexpressed CREB1 had contrary results. CREB1 was found to be targeted by miR-433, as verified by a luciferase activity assay. Conclusion: We found that DNA methylation can downregulate miR-433 in NSCLC, which promotes the malignant behaviors of NSCLC cells.